Mosquito Deer tickIxodes scapularis Some ticks can go without food or water for up to 200 days while waiting for a meal to pass by.

Ticks have been around since the Cretaceous, so dinosaurs might have been plagued by ticks, too.

Of the about 800 species of ticks worldwide, 90% are associated with wild mammals, birds and reptiles. The other 10% can transmit disease to humans (such as rickettsiosis and Lyme disease) and domestic animals (like babesiosis and swine fever). There are two main types of tick: Argasid ticks (soft-bodied ticks) have as many as seven immature stages and several blood feeding episodes at each stage. Ixodid ticks (hard- bodied ticks) have three distinct stages. All ticks need blood at every stage of their life cycle.

Many tick species are host specific and do not stray far from their preferred hosts because they are obligate blood feeders. Soft ticks tend to stay within the nests or burrows of their hosts. In contrast, hard ticks usually live apart from their host, in soil or leaf litter, between their three blood-feeding episodes. Deer tick mouthparts have a large hooked probe that the tick uses to stay attached to the host for three to five days or longer. The adult female takes an extremely large blood meal to provide the necessary protein for egg development.

Engorged female dog tick with eggs.Dermacenter variabilis Adult female Ticks are not insects—they are arachnids and belong to the same group that contains mites and spiders. Adult ticks have four pairs of legs, insects only three pairs. Ticks never have wings. Their mouthparts are completely different from those of insects, even those that feed on blood.